The SERVA-Cell is a rigid air filter engineered to provide medium and high efficiency filtration combined with a prolonged life cycle. The box filter construction eliminates the need for retainers and special external wire media supports. Its rugged design and construction make the SERVA-Cell effective in challenging applications where high humidity, turbulent airflow, intermittent water exposure, and elevated operating temperatures exist. The filter pak consists of a continuous sheet of non-combustible waterproof microfiberglass media pleated around radi-edge, corrugated aluminum separators. The pak is enclosed in an all-metal, corrosion-resistant 28 gauge galvanized steel casing. UL Class 1